Modern stock DLSR's vs Older modded DLSR's for AP

[Chris]

After failing to get my modded 350D to focus with prime camera lenses, I'm wondering where to go from here? 

I could buy a small fast reflector and the camera would reach focus fine, but then I would be pushing the limits of my EQ3 a bit with the longer focal length. Or I could change the camera for a stock Canon DLSR around the same value perhaps? (350D, 400D, 20D), these being non modded would work with my lenses but wouldn't be great for H-Alpha signal, Hmm?

Now, I've heard someone mention that a stock 600D out performing an older modded 450D for H-Alpha. If this is true or there abounce, I would be interested in buying a newer non modded model for both daytime and astro. I'm aware of the Baader replacement filter modded cameras sold by cheapastrophotography which is also an option.

So I'm calling all DLSR imagers for opinions please, do modern stock cameras have adequate/improved sensitivity to Ha?  

 

    

[RikM]

If you give it enough exposure time, you can get quite a bit of Ha on even a stock 1000D

[Alien 13]

The modern Canons do seem to have better Ha response and of course lower noise I have never felt the need to mod mine.

Alan

[happy-kat]

I must have missed you focus troubles post Chris. In what way are you not able to focus?

[Chris]

3 hours ago, RikM said:

If you give it enough exposure time, you can get quite a bit of Ha on even a stock 1000D

 

Ok thanks Rik, I'm impressed . I did once have a stock 1100D, but only ever imaged galaxies with it.

Stars and nebs are more on the menu with camera lenses, but as long as long as your 1000D image wasn't a ridiculously long exposure time? I think I can live with a stock older model Canon for the time being.

Infact after seeing your pic I decided to bid on a few cameras on fleabay; bagged a nice condition Canon 30D. It didn't break the bank at 77 quid and at least I shoud be able to focus it! lol

Cheers

[Chris]

1 hour ago, Alien 13 said:

The modern Canons do seem to have better Ha response and of course lower noise I have never felt the need to mod mine.

Alan

Thanks Alan  It's good to have a second opinon on this, it's surprising how little there is on the net regarding this question! 

It's good to know that if and when I upgrade, it will make a difference. Still, the case for the older stock cameras doesn't seem as bad as I thought, so the 30D should keep me happy for a while hopefully.   

[Chris]

28 minutes ago, happy-kat said:

I must have missed you focus troubles post Chris. In what way are you not able to focus?

Hi  I basically couldn't focus on stars with either of my lenses (55mm and 135mm Super Takumars and infinity m42 to EOS adaptor). It turns out that modding the 350D alters the focus point, which is fine for a scope, but not for lenses which have much less focus travel.

I started a thread on it, and had a couple of suggestions how to fix it. One was to unscrew the outer lens ring and turn it slightly so the lens goes beyond infinity, I tried this and still couldn't get it to work so put it back.

I then thought about buying a scope to get the camera to focus, something like a 150p/130pds, but I'm only using an eq3 so tracking at focal length might be a problem. I've just flogged my daytime compact camera and used the money to buy a stock Canon 30d body. This should hopefully work for both daytime plus astro as it appears you can pull some of the red stuff out with stock cameras looking at Rik's image

I not sure, but I might sell the modded 350D to someone with an imaging scope.   

[Gina]

Asahi Takumar, Super Takumar and SMC etc. lenses have a back focus of 45mm whereas Canon EOS models have 55mm back focus.  It's a problem

[Chris]

4 minutes ago, Gina said:

Asahi Takumar, Super Takumar and SMC etc. lenses have a back focus of 45mm whereas Canon EOS models have 55mm back focus.  It's a problem

Oh dear!  Well the lenses are close to focus with the modded 350D when the aperture is stopped right down. And I reckon focus will be around 2-3mm further forward with the stock 30D, but from what you've just said, I won't hold my breath  

[Dr_Ju_ju]

I've had my 600D & 1100D (on its way back) modded by Juan @ cheapastrophotography (wonderful service BTW), & he re-shims the sensor to keep the correct spacing.

I can report that with my 600D, I can achieve focus with stock Canon lenses but also the Super Takumar M42 lenses I have.

[happy-kat]

Can't you get /fit a spacer to get a bit more travel.

[Chris]

21 minutes ago, happy-kat said:

Can't you get /fit a spacer to get a bit more travel.

Do you mean reshimming the chip to bring it forward? if so, I used to enoy modding cameras, did a few 350D's infact, but now I've got serveral young kids running around plus no table to work on, it wouldn't be as easy as it was before. Oh, and when I say easy I mean really tense and anxious trying to get those pesky ribbon cables back in! lol 

[RikM]

26 minutes ago, happy-kat said:

Can't you get /fit a spacer to get a bit more travel.

No. The sensor is too far back once you remove the internal filter. Adding a spacer would make it worse. Shimming the sensor forwards or fitting a replacement filter to retain the focal point are the only options I am aware of.

I have a filter-removed 350D and that doesn't reach focus with standard lenses either. 

[Gina]

Adding a filter such as Ha or UVcut will bring the focus back for Canon lenses.  This is what I've done.

[Chris]

41 minutes ago, Gina said:

Adding a filter such as Ha or UVcut will bring the focus back for Canon lenses.  This is what I've done.

Hi Gina  can I ask exactly which filters you use for this please?

[Gina]

Yes indeed - Baader 36mm unmounted narrow band filters.

I can't remember which UV cut filter I used - it was mainly to provide a sealed enclosure containing silica gel to stop condensation on the sensor when cooled.

[Psychobilly]

13 hours ago, Gina said:

Asahi Takumar, Super Takumar and SMC etc. lenses have a back focus of 45mm whereas Canon EOS models have 55mm back focus.  It's a problem

M42  (M42x1.0mm pitch) mount register is 45.46mm  Caonn EF/EF-S is 44.0  T mount (M42x0.75mm pitch )is 55.00 mm Hence the need to  use of a thin M42 to EF adaptor (1.46mm difference)

I use this site for register info when considering possible lens ...

http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html

Peter...

 

 

[Gina]

Looks like I'm wrong on the EF / EF-S back focus - I have it ingrained in my memory that it was 55mm but where I got that from I don't know   Guess my memory is playing tricks on me.  Wouldn't be the first time   Sorry folks

[Chris]

2 hours ago, Gina said:

Yes indeed - Baader 36mm unmounted narrow band filters.

I can't remember which UV cut filter I used - it was mainly to provide a sealed enclosure containing silica gel to stop condensation on the sensor when cooled.

Thanks Gina  I see now, they are the exact thickness of the filter taken out of the 350D which is quite handy. I'll look to see if there is a more budget way of doing the same, maybe kill two birds with one stone by fitting a 2mm ish IR block filter    

[Gina]

I must check out using Asahi Pentax type lenses with DSLRs - looks like it should be possible after all   May need to remove the Canon mount and replace it with a 42x1mm threaded ring.

[Skyline]

I have found the stock 1100D and the 600D a little more sensitive in Ha then the older models, but I have found after modding them they are Ha Hoovers !

I always found the Gary Honis guides quite informative on how to mod DSLRS.

Al.

[Chris]

2 minutes ago, Skyline said:

I have found the stock 1100D and the 600D a little more sensitive in Ha then the older models, but I have found after modding them they are Ha Hoovers !

I always found the Gary Honis guides quite informative on how to mod DSLRS.

Al.

Good to know that the latest models don't absolutely need modding to begin with, and that you will get something out of them. I've made my bed for the time being with the 30D and modded 350D, but it's all good info for the future  

Agreed about the Garry Honis guide, it's excellent, I used it a few times before the kids came along. I've been out of the imaging game for a while now.    

[Skyline]

And there's  me thinking you didn't miss it 

[Chris]

8 minutes ago, Skyline said:

And there's  me thinking you didn't miss it 

haha! Visual astronomy is really relaxing, but I do miss the buzz from imaging. I don't know if I'm being practical trying to image again with the kids being so young, but my mate Dan-k is giving it a go with 3 young kids so I'll give it ago too